Many persons performing work on a keyboard and with a computer mouse suffer muscle cramp, with medical consequences. For ceramic decorators and goldsmiths there are benches (partially raised) which have a round cut-out at the front and so partially surround the persons working there. However, this arrangement cannot be used with computers and in offices as it would probably be considered unacceptable both for space and optical reasons in the case of computer workplaces.
Devices have been invented to be placed on the desk in front of the keyboard and provide support for the wrist. However, this method is inflexible and, because of the friction and the posture of the hands, still unergonomic.
The moveable constructions of the types already invented for fitting on the work desk all suffer from the primary fault that they allow kinetic energy to be transmitted to the desk, that they are too massive and complicated, and that they require maintenance for proper functioning as they otherwise produce noises or do not move easily. They are mostly visually obtrusive. Also the mounting of the rest device on the desk often causes problems.
A support for the forearm for people operating computer mouse is already known from DE 92 07 271 U1. This forearm support has a clamp 1 for securing the device to the desk top, and a pivot mechanism. If the forearm is resting on this support and if, for example, it is desired to move the mouse in a linear direction towards the pivot, this support acts counter to the movement of the forearm by unavoidably moving the fore-arm in an arc, despite an intended straight line movement. The user has to try to compensate the "misguidance" given by this support. This support is therefore unsuitable.
DE 29 10 855 A1 describes a typewriting support for the hands. A long, ovally rounded supporting bar is fitted between two other fork-like bars and provides support for the wrists during typewriting. The fork-like bars are equipped with screw clamps for mounting the device on the desk. The device transmits kinetic energy to the desk and so may disturb the monitor; therefore, sturdy desks are required, which also have to be specially shaped. The device gets in the way of the user's body and also takes up space. Being large, it is visually unattractive. During movement, friction occurs between the support bar and the arms; the user is consciously aware of it and finds it a nuisance. The moving joints have to be serviced. It is evident that this typewriting support is only designed for operating a typewriter keyboard and is neither intended nor suitable for using a computer mouse.
DE-GM 19 83 548 describes a sprung apparatus for supporting the elbows during typing. A hollowed rest for one elbow is mounted on one end of a telescopic strut, and a clamping device for mounting the sprung telescopic strut on the seat of a chair on the other. The construction is fitted to the seat of the chair, so that every movement of the chair transmits a movement to the arm. Problems are also to be expected in resolving the height differences between the desk and the chair, which can mean that only special furniture may have to be used. The telescopic arm requires technical maintenance, otherwise it may easily jam, and it has to be a correspondingly heavy and expensive construction to ensure that it operates reasonably easily. It is visually obtrusive because of its size. It is evident that this elbow support is not suitable for operating a computer mouse, as it even hinders the movement of the forearm required for moving the mouse.
GB 22 52 530 A describes an armrest for supporting the forearm of a typist. As already detailed in the first reference described above, this proposal for a forearm support only involves the use of three joint 18, 26 and 32, located between two arms 20 and 28. The first joints 32 is mounted on a device which can be clamped to a table and is rotatable in one plane; the second arm 20 is mounted on the middle joint 26 and is vertically rotatable on the same axis, and the outer end of the second arm 20 is provided with a hollowed armrest 12 which has a pivoted mount. As already detailed in the first reference described above an arrangement of this kind acts counter to the movement of the forearm during operation of a computer mouse, so that the user has to additionally concentrate on the "misguidance" caused by this construction, and has difficulty compensating this misguidance. It destroys kinetic energy through friction in the joints, which in turn can only be reduced by special (ball) bearings. The clamp fixings on the desk can work loose and may damage the desk. The construction can only be removed with difficulty by releasing the screws when it is not required. It is obstructive and takes up space on the desk top. This device is therefore likewise not suitable, and not intended, for the operation of a computer mouse.
U.S. Pat. No. 5,472,161 describes a support for the wrists during the operation of a typewriter keyboard. This known support consists of a bracelet on which a kind of "wheeled trolley" is fitted that lifts and supports the wrists and can be moved about on the desk top. This device has to be strapped to and unstrapped from the arm every time it is used, and it may cause problems to the skin of the user's wrist. The desk top always has to be clear. The height of the arm is not adjustable, or only to a limited extent. Movement towards the back of the desk top is restricted, as the rollers are impeded by the keyboard or other objects. The rollers have to be serviced because if they do not run easily, through soiling, they are more of a hindrance than a help. This arm support is neither suitable nor intended for the operation of a computer mouse. A wrist support of this kind on rollers would constantly come up against the mouse pad and would only hinder operation of the mouse.
U.S. Pat. No. 4,822,103 relates to a forearm support which is mounted on the left and right of a chair seat. A vertical arm 3 is provided at its upper end with a support 1, which is ball-mounted and can move forwards and backwards following the movement of the forearm. When no force is exerted by the forearm, springs 9 and 10 return the support 1 to its initial position. This known forearm support is neither suitable nor intended for supporting the forearm during the operation of a computer mouse. Because of its design, it only supports the operation of operating controls which are located in the immediate vicinity of the user's chair. Moreover, it only supports a forward and backward movement of the forearm. This forearm support is specifically designed for moving a lever or such like forwards and in a straight line from a rest position into an operating position and back, as it returns the forearm to the initial position via springs 9 and 10. It is evident that such a support is unsuitable for the operation of a computer mouse and indeed would hinder such use, as the user is already sufficiently occupied with preventing the return of his forearm to the initial position.
FR 1 082 209 A describes a forearm support for location between the seats of a vehicle. This device is adjustable for height and has a support surface 26 which, adjusted to the seat position of the occupant of the seat, can be moved forwards and backwards and fixed in a pre-set position. It is evident that this device is neither suitable nor intended for supporting the forearm during the operation of a computer mouse.
Finally, U.S. Pat. No. 4,069,995 describes an arm support with three or more pliant support elements 12, 14 and 16, arranged vertically in a regular polygon between a (complicated) desk 18 and a base plate 20 (which can be viewed as a foot). In the center of the base plate 20 is a height adjustable cylinder 38 which is provided at its top with a forearm support 22 which is (only) tiltable by means of a pivot 34; as a result, the support always falls into an inclined position when not in use. If the forearm is moved from its resting position, the desk also moves, whereby the desk 18 remains parallel to the base plate 20. If the force exerted by the forearm is released, the arrangement returns the forearm to its resting position by means of the pliant supports. This armrest is mounted on the side of the seat of the chair on which the user is sitting and is therefore not suitable nor intended for free-standing use on the floor, and is therefore neither suitable nor intended for the operation of a control element lying or standing on a desk, such as a computer mouse. Additionally, the degree of movement allowed would be too small for the operation of a computer mouse or the like, and the constant return of the foreman to its resting position would be inconvenient. This armrest is very complicated in design and complicated to manufacture, making it expensive, clumsy and unacceptable.